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Friday, October 28, 2011

On October 19.5, 2011 we started an observing session to recover the periodic comet 171P/Spahr. T. B. Spahr (then at University of Arizona, Arizona, USA - now Director, Minor Planet Center) discovered this comet with the 0.41-m f/3 Schmidt telescope in the course of the Catalina Sky Survey on 1998 November 16.39.

We found an object of magnitude ~20.6 with the following offset from the nominal position of comet 171P (RA 2.5'W DEC 0.6'S). We found again the same object on October 20.5 & October 24.5. A faint possible tail, about 20-arcsec long toward North-East is visible. We imaged it remotely with the 2.0-m f/10 from the Siding Spring-Faulkes Telescope South.

Below you can find our recovery image of October 24, 2011:

While below you can see an animation showing the movement of the comet (click on the thumbnail for a bigger version):

Before our recovery, comet 171P/Spahr was last observed on February 06, 2006.

Thursday, October 27, 2011

Cbet nr.2875, issued on 2011, October 26, announces the discovery of a new comet (discovery magnitude 19.4) by Terry H. Bressi on CCD images obtained on September 24, 2011 with the Spacewatch 0.9-m f/3 reflector at Kitt Peak. The new comet has been designated C/2011 U2 (BRESSI).

We performed some follow-up measurements of this object, while it was still on the neocp. Three stacked 60-s R-band exposures taken remotely on Oct. 25.5 with the 2.0-m f/10 "Faulkes Telescope North" at Haleakala show that this object is a comet with a compact coma about 4" x 3" in size, elongated toward p.a. 250 deg, with a sharp central condensation and a tail about 20" long in p.a. 250 deg.

Monday, October 24, 2011

The *big* problem imaging the "debris" of C/2010 X1 (Elenin),
is the low S/N of the little cloud it left away. If you want to
integrate enough, in order to increase the S/N of yours images, then you
face the problem of the trailed stars that are crossing the field,
producing an annoying interference with the faint cometary cloud.

A professional astronomer (CARA's collaborator Gian Paolo Tozzi,
Arcetri Observatory, Italy), suggested to shoot again the field of the
comet with the same instrumentation when the comet moved away, and then
to subtract the field stars from the cometary original images you want
to enhance. In principle, this would help to eliminate at least some
part of the disturbing effect produced by the trailed stars.

We tried this interesting technique on the images we obtained on 2011 Oct. 23.37 (see our previous post), and we obtained the following result (click on the thumbnail for a bigger version):

We have still to improve this method (we found some issues matching the size of the field stars, due to the different seeing conditions and/or focus on two consecutive nights), anyway the results looks pretty promising. The image treated in this way, is significantly cleaner, and some features of C/2010 X1 (Elenin) are easier to be seen. In particular, the sunward part of the "cometary cloud" appears much sharper compared to the antisolar direction. The diffuse shape of the comet appears to be somehow "conical", about 1.5 deg long overall, with a maximum thickness of about 10-arcmin in the solar direction: the ovate shape of the "cometary cloud" than thinners tailward. We failed to find any convincing condensation within it, provided that the few "knots" visible on our image, are probably due to some noise left by the star profile removal process.

Talking about morphology, it's interesting to notice some similarities of what we found in our image, with this archive image of comet Shoemaker-Levy 9, seen after its break-up (Lowell Observatory 1.1m Hall telescope of 23 June 1993):

UPDATE OCTOBER 25, 2011

Below you can see a new elaboration of the previous image (click on the thumbnail for a bigger version):

Friday, October 21, 2011

Today, we imaged again the field of C/2010 X1 (Elenin) remotely, from the GRAS network (Mayhill station, NM). We used two scopes, nearly simultaneously: the 254mm, f/3.4 reflector + CCD, and the 0.1m, f/5 APO refractor + CCD.

The first observing session, on 2011 Oct. 21.3861 UT, through the 10" reflector (15x20sec, unfiltered exposures, scale 1.6"/px, field of view 59'x40'), provided no obvious moving objects in the field of view.

The second observing session with the APO refractor, was scheduled on two separate slots, spaced by about 2h, on 2011 Oct. 21.38392 and Oct. 21.47579. The first sequence was a stacking of 9x30sec, the second was 11x30 sec (unfiltered exposures, scale 3.5"/px, field of view 3.9 degx2.6 deg). Blinking the two fields, we found something moving on the sky background (moonlight interference).

After some image processing, to clean a bit the image, we get this result (click on the thumbnail below to see the animation):

If this *extremely* faint and diffuse blob of light is not an artefact (stray light reflection, ghost image, etc.), it is very close to C/2010 X1 ephemerids position, and it seems to moves with the appropriate proper motion.

We encourage other observers to confirm or refute this possible find we made, with their own observations/images. We suggest the use of wide-field, fast focal ratio scopes, possibly under very good sky conditions.

UPDATE October 23, 2011

Following our yesterday's report of the recovery of the remains of comet C/2010 X1 (Elenin), we confirm the detection of the "cloud" on today observations too.

Here is again the "cloud" imaged by our team few hours ago on October 23.4, 2011 remotely from the GRAS network (Mayhill station, NM) by 0.1m, f/5 APO refractor + CCD (12x300-seconds exposures). Click on the thumbnail for a bigger version:

The "cloud" is roughly 40' long with an extension of 6' near the expected position of the comet.

Here you can see an image where the X marked the ephemeris position for comet C/2010 X1 (Elenin). Click on the thumbnail for a bigger version:

And this is an animation showing the movement of the "cloud" along with to the movement of the expected comet's position (click on the thumbnail for a bigger version):

The fast streak moving on the right side of the animation is the PHA asteroid (138524) 2000 OJ8 (magnitude 14.5).

After our request to other observers to try to confirm our find, we have received the following images and animation by fellow observers that seems to confirm the presence of this faint and diffuse "cloud" moving at the same speed and PA of the comet C/2010 X1 (Elenin) very close to C/2010 X1 ephemerids position.

The image by Rolando Ligustri obtained remotely from New Mexico on October 22, 2011 (the image processing was particularly forced to highlight the faint nebulosity):

The animation by Leonid Elenin on October 22, 2011 (click for a bigger version)

The animation by Juanjo González Díaz on the evening of October 21, 2011 (click for a bigger version)

Cbet nr.2867, issued on 2011, October 21, announces the discovery of a new comet (discovery magnitude 19.1) by A. D. Grauer on CCD images obtained on October 19, 2011 with the Mount Lemmon 1.5-m reflector.

According to the CBET: "After two nights of observations of Grauer's comet had been received at the Minor Planet Center, T. Spahr realized that this object was identical with an object discovered a year ago by the LINEAR project (discovery observation tabulated below; cf. MPS 351583) that appeared to be a Jupiter Trojan minor planet."

The new comet has been designated P/2010 TO20 (LINEAR-GRAUER).

We performed follow-up measurements of this object on 2 different nights, while it was still on the neocp.

Stacking of 5 R-filtered exposures, 60-sec each, obtained remotely, from the Haleakala-Faulkes Telescope North by G. Sostero, N. Howes, E. Guido on 2011, Oct. 20.4, through a 2.0-m f/10.0 Ritchey-Chretien + CCD, confirms that this object is a comet: we found again a sharp central condensation, a compact coma about 6" in diameter, and a tail, at least 30" long, toward PA 247.

Monday, October 17, 2011

On Saturday October 15, 2011 a bright (magnitude 13.5) and fast object (observed by 703 Catalina Sky Survey) was published on the Neocp list with the designation ST37690.

We performed some follow-up measurements of this object while it was still on the neocp on October 15.5 remotely from the GRAS Observatory (near Mayhill, NM) through a 0.25-m, f/3.4 reflector + CCD. Soon after ST37690 object was removed from Neocp list because it was not a minor planet.

As it turned out, ST37690 was actually the artificial satellite SPEKTR-R (official designation 2011-037A). Spektr R is a Russian orbital radio telescope, and currently the largest space telescope in orbit.

"Spektr R, a Russian radio astronomy satellite, was launched from Baikonur on 18 July 2011 at 02:31 UT by a Zenit 3F rocket. Spektr R is one element of an international network of observatories in a project called RadioAstron. Funded by the Russian Astro Space Center, Spektr R features a 10-m diameter antenna reflector designed to help astronomers see deeper into supermassive black holes, obtain views of collapsed stars, and better measure the influence of dark energy on the cosmos. When linked together, RadioAstron's telescopes have a resolution of 7 microarcseconds"

Tuesday, October 11, 2011

Recently we tried to image C/2010 X1 (Elenin) after its solar conjunction. The observing conditions for this comet are currently quite difficult: very low in the morning sky at twilight, within the zodiacal "light pollution".

Anyway we decided to go with several robotic scopes, operating under excellent sky conditions (New Mexico and Mauna Kea). At first we aimed at the expected comet's position (MPC ephemerids) on 2011, Oct 09.5, through a 0.25-m f/3.4 reflector + CCD and, nearly simultaneously, through a 0.10-m f/5 APO refractor + CCD, from the Global Rent a Scope facility (near Mayhill, NM).

Stacking of a number of images, we observed no distinct evidence of the comet within about 30 arcmin of the expected position, with a limiting magnitude around 17, and to limiting magnitude about 15, within about 2 deg from the expected position. Below you can see the crop of the 0.25-m reflector stacked image set (click on the image for a bigger version):

On 2011, Oct. 10.6, we imaged the area where comet Elenin was supposed to be, through the 2.0-m f/10.0 Ritchey-Chretien + CCD of Faulkes Telescope North (Mauna Kea, Hawaii). Stacking several exposures, with limiting magnitude at around 20.5, doesn't show any trace of the comet within the 10'x10' field of view centered on the comet's ephemerids (while stacking these images along the proper motion of the field minor planets, we can easily distinguish the asteroid (43629), with its magnitude at 20.3 (click on the image for a bigger version):

Monday, October 3, 2011

Cbet nr.2852, issued on 2011, October 02, announces the discovery of a new comet (discovery magnitude 15.7) by R. A. Kowalski on CCD images obtained on September 30, 2011 with the Catalina Sky Survey's 0.68-m Schmidt reflector. The new comet has been designated C/2011 S2.

As noted on both the discovery Cbet & Mpec:

"The orbit of this object is essentially indeterminate at the present time. It is possible that this is a short-period comet. Among the wide range of possible short-period orbits are orbits that appear similar to P/2006 T1 (Levy). Initial attempts to link the two apparitions have not been successful. Further observations are encouraged."

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 30 unfiltered exposures, 30-sec each, obtained remotely on 2011, October 01.4 from the GRAS Observatory (near Mayhill, NM) through a 0.25-m, f/3.4 reflector + CCD, shows that this object is a comet with a condensed coma about 10-arcsec in diameter, elongated, toward PA 295.

Sunday, October 2, 2011

A new bright comet diving into the Sun is visible right now (October 01, 2011) in C3 and C2 images taken by SOHO spacecraft. This object belong to the famous Kreutz-group, a family of sungrazing comets that are named after German astronomer Heinrich Kreutz who first studied them in the details. These comet fragments passes extremely close to the Sun at perihelion and usually they completely evaporated during such a close approach. The comet (designated SOHO-2143) was discovered on Sept. 29th by a group of four independent SOHO comet hunters (M. Kusiak, S. Liwo, B. Zhou and Z. Xu), who reported it within 9-secs of each other!

According to Karl Battams: "It's *very* rare for a comet to enter the fov as bright as this one. I think this is the brightest SOHO Kreutz we've ever seen!"

SOHO-2143 is strongly saturating C3 Images - (click to see a bigger version)

Comets & Asteroids news

Welcome to our Astronomy blog, devoted in particular to Comets & Asteroids and related topics. This blog is maintained by Italian amateur astronomer Ernesto Guido, particularly active in the study of the small bodies of the Solar System.